Fair Value Measurement and Election - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Estimated Fair Value of Loan Portfolio's Net Carrying Value, Percentage	102.00%		102.00%		101.00%
Assets	$ 198,892		$ 198,892		$ 190,817
Loans Receivable, Fair Value Disclosure	246		246		257
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	0			$ 0
Allowance for Loan and Lease Losses, Write-offs	167	$ 123	278	254
Unfunded loan commitments and letters of credit	63,900		63,900		66,200
Allowance for unfunded loan commitments and letters of credit	69		69		66
Total Return Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Loans Receivable, Fair Value Disclosure					2,200
Interest Rate Lock Commitments [Member]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	87	$ 37	116	$ 97
Trading Account Assets [Member] | Commercial and Corporate Leveraged Loans [Member] | Fair Value, Inputs, Level 2 [Member]
Loans Receivable, Fair Value Disclosure	423		423		356
Commercial and Corporate Loans [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Assets	445		445		525
Commercial and Corporate Loans [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | Preference Shares [Member]
Assets	3		3		2
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Loans Receivable, Fair Value Disclosure	0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Loans Receivable, Fair Value Disclosure	0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Loans Receivable, Fair Value Disclosure	246		246		257
Lease Agreements [Member] | Fair Value, Measurements, Nonrecurring [Member] | Other Assets [Member]
Asset Impairment Charges	4		4		6
Equity Method Investments [Member] | Fair Value, Measurements, Nonrecurring [Member] | Other Assets [Member]
Asset Impairment Charges	8		8
Other Real Estate Owned [Member] | Fair Value, Measurements, Nonrecurring [Member]
Asset Impairment Charges	1		1		4
Collateralized Debt Obligations [Member]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3			0
Other Assets [Member] | Fair Value, Measurements, Nonrecurring [Member]
Asset Impairment Charges	24		24		$ 6
Building [Member] | Fair Value, Measurements, Nonrecurring [Member] | Other Assets [Member]
Asset Impairment Charges	7		7
Land [Member] | Fair Value, Measurements, Nonrecurring [Member] | Other Assets [Member]
Asset Impairment Charges	$ 5		$ 5